Automatic circuit breaker and similar electrical switchgear



Aug. 28, 1951 E. BESAG ET AL 2,565,468

AUTOMATIC CIRCUIT BREAKER AND SIMILAR ELECTRICAL SWITCHGEAR Filed Aug. 10, 1948 5 Sheets-Sheet l fimufim wim 1w 2 Jim B M; W M

-.2 1951 E. BESAG ET AL 2,565,468

AUTOMATIC CIRCUIT BREAKER AND SIMILAR ELECTRICAL SWITCHGEAR Filed Aug. 10, 1948 5 Sheets-Sheet 2 EWAL 8.71% i mmwwaww Attorneys.

Aug. 28, 1951 E. BESAG ET AL 2,565,468

' AUTOMATIC CIRCUIT BREAKER AND SIMILAR ELECTRICAL SWITCHGEAR Filed Aug. 10, 1948 3 Sheets-Sheet 5 'mam pmawwgm 3 s e Z 2 y I m M Attorneyfi.

Patented Aug. 28, 1951 AUTOMATIC CIRCUIT BREAKER AND SIM- ILAR ELECTRICAL SWITCHGEAR Ernst Besag and Walter Edward Hill, Streetly,

and Thomas Daniel Guy Wintle, Walsall, England, assignors to J. A. Crabtree & Co. Limited, Walsall, England, a British company Application August 10, 1948, Serial No. 43,496 In Great Britain August 14, 1947 Claims. 1

This invention relates to improvements in electromagnetic switches, and is particularly concerned with automatic circuit breakers and similar electrical switchgear, the invention being concerned with means for the mounting of the traverse of an armature of a motor starter or contactor switch, such armature co-operating with a magnet and carrying contacts engageable with fixed main contacts.

The principal object of the invention is to provide an improved construction occupying only a small space and adapted to minimise friction and facilitate movement of the traverse. A further object is to ensure such relation between spring pressures acting on the traverse and the contacts for obtaining efficient operation and ensuring adequate pressure for overcoming residual magnetism. Another object is to associate with the traverse, means occupying only a small space for the actuation of additional main or auxiliary contacts.

According to this invention, the armature traverse is adapted to move in a direction approximately horizontal and parallel to the lines of force of the magnet and is mounted on a pivotally mounted carrier. The pivotal support for the sliding traverse minimises any tendency for it to jam, while avoiding the necessity for the production of accurate guideways. The carrier may be moved against spring pressure which is adapted to be reduced during the movement to the on position, thereby reducing the torque required for its operation and enabling the employment of relatively strong springs for the main contacts. For this purpose, the traverse may be mounted freely on the upper ends of the limbs of a U-shaped carrier, such arrangement providing a two-point suspension. The carrier may be provided with a pair of rearwardly extending arms each adapted for the actuation of additional contacts. The provision of two arms extending from a single member ensures equalisation in compression of the springs if uneven pressure be applied to the member, and prevents any tendency of the traverse to jam during its sliding movement. The additional or subsidiary contacts are preferably arranged to make earlier, and break later, than the main contacts which are carried on the front of the traverse. Such an arrangement minimises the wear on therearwardly disposed contacts and practically confines the wear to the main contacts which are more easily accessible for inspection and replacement. The moving plates for the additional contacts are disposed horizontally and are movable in the vertical plane, that is, at right angles to the horizontally moving armature, whereby any tendency to bounce is reduced with accompanying reduction in contact wear.

In order to enable the invention to be readily understood, reference will now be made to one example of construction in which:

Figure 1 is a central Vertical section, the chain lines indicating the position of the pivotal carrier in the on position.

Figure 2 is a perspective view of the rocker or carrier and the moving member of the additional contacts.

Figures 3 and 4 are diagrammatic views of the respective positions of the spring arrangement for the rocker or carrier.

Figure 5 is a perspective view of the auxiliary box for the additional contacts.

Figure 6 is a front elevation of the switch.

Referring to the drawings, a traverse h carrying the armature i, is slidably mounted between upper and lower boxes no secured to a mounting plate 11. The main moving contacts 4 on the traverse, are provided at each end with a button engageable with a fixed contact 5 on the front of a box, and are subjected to resilient pressure by springs 6 received in recesses 6 of the traverse. In the upper box n are mounted thermal release devices, each of which comprises a heater coil 1 around which is disposed a bimetal element 8 operative on a trip device 9. In the lower box 0 there is mounted an insulating carrier a of U-shape in front elevation and pivoted at each end of its lower corners in recessed lugs D, such arrangement enabling pivot mountings to be effected by the bearing of the moulded parts on each other at points free from moulding flashes. The carrier 41 is held seated in these lugs b by a pair of helical compression springs e encircling pairs of guiding plates 1 and disposed so that, together with a limb a of the carrier, each spring presents a V shape when viewed from the side as seen in Figures 3 and 4. Each spring e surrounds two fiat plates disposed in face-to-face, relatively slidable relation and 3 urged in opposite directions by spring e. Each end of the plate has at one end thereof an arrow head formation for bearing in a recess 9' at the lower end of a limb a and against a recess of the box, the spring e engaging the bases of the arrow head formations on adjacent plates and tending to move said plates axially in opposite directions.

Nose formations g on the upper end of each limb of the carrier a are adapted for; carrying an insulating traverse h in which is mounted a laminated armature 2 of E-shape in plan. This armature i co-operates with a reversely disposed E-shape magnet k around the centre limb of which is disposed a coil m, the armature bein restrained by the engagement of its traverse h with the lower box 0 and the upper box 17. to

-move in a direction substantially parallel to the lines of force of the magnet. Hook formations 0 on the armature provide for its releasable mounting on the carrier at and enable it to be pivoted thereon during the sliding movement of the traverse for a switching operation.

Each spring e acting through sliding plates f is operative on the lower end of each limb a of the carrier a, so that as the traverse moves to the on position, the springs e are compressed although the resultant arm a; on which each spring works is reduced, thereby reducing the torque. to such an extent that the eilort of the spring practically disappears as the angle between the carrier and the spring diminishes as seen in Figure 4. The limbs a of the carrier a may be grooved as at a on their rear faces for closing over the springs as the traverse moves to the on position.

Rearwardly extending. from the carrier are two arms 10 constituting bell cranks, the ends of which protrude into openings in a transverse member 7" which is movable-in vertical guides in an auxiliary box 0 (see Figure in the lower box. On this transverse member 1" are disposed contact plates 8, each of which is embraced by the inwardly turned ends of a U-shaped member 1) disposed in a deep recess in the member and acted on by helical compression springs w, for seating the plate on a pair of fixed contacts t. Each fixed contact t is secured to the box 0 by a screw I and is in the fornr of a bent strip, the lower end of which depends below the box for constituting a terminal end 2. These ends 2 are bent obliquely to the vertical plane and are also preferably disposed at an angle relatively to each other so as to facilitate access from the front without interfering with the conductors leading rearwardly from the mainterminals 3 which are disposed at the front of the switch. The contacts st may be employed for the purpose of effecting change over from star to delta, or for speed changes, and are preferably arranged to make earlier and break later than the main contacts 4, 5; Ifdesired, the arrangement may be modified sothat the contacts are broken instead of being made on actuation of the carrier to the on position.

Having thus described our claim:

1. An electromagnetic switch comprising vertically spaced upper and lower boxes each having invention, We

a stationary contact thereon; an insulating traverse having an armature mounted thereonv and having contacts thereon adapted upon movement of saidtraverse to make and break said stationary contacts, said traverse being'floatingly slidable with clearance between the opposed faces of said upper and lower boxes in a substantially horizontal direction; an electromagnet mounted between said upper and lower boxes and in substantial horizontal alignment with the armature on said traverse, said electromagnet, upon energization, attracting said arm- .ature and moving said traverse to bring the contacts thereon into engagement with the contacts on said upper and lower boxes; and a carrier having its lower end mounted for pivotal movement' in saidv lower box and its upper end engaging and supporting said traverse, said carrier constituting the main support for said traverse during its substantially horizontal movements toward and away from said electromagnet.

2. An electromagnetic switch as defined in claim 1, in which the upper box is readily removable whereby the traverse may, upon removal of said upper box, be readily lifted from engagement with said carrier.

3. An electromagnetic switch as defined in claim 1, in which the traverse is supported on said carrier approximately midway of the length ofsaid traverse.

4. An electromagnetic switch as defined in claim 1- in which spring means extends between the lower box and said carrier and is effective on opposite sides'of the axis of pivotal mounting of said carrier, which spring means is compressed as the carrier moves from off position to'mid position and subsequently expands as said carrier moves from mid position to on position,

thus reducing the torque required for operation of said switch as it moves from its mid position to 1ts"onposition.

5-. An electromagnetic switch as defined in claim 1, in which a pair of auxiliary, fixed contacts is mounted in the lower box, and in which cooperating contacts actuated by said carrier are movable into and out of contact with the auxiliary', fixed contacts in the lower box upon movement of said carrier.

6. An. electromagnetic switch as defined in claim 5 in which the cooperating contacts acmated by movement of the carrier are movable. in a plane at right angles to the plane of movement of said traverse.

7. An electromagnetic switch as defined in claim 5. in which the carrier is provided with arms which, upon movement of said carrier by said traverse, cause movement of the cooperating contacts into and out of contact with said auxiliary,

fixedcontacts.

8. An electromagnetic switch as defined in claim 1, in which the carrier includes at least one substantially vertical arm having another arm extending rearwardly therefrom at its lower end and in a substantially horizontal direction, and in which a compression spring acts between a portion. of the lower box and the angle between said two arms, the disposition of said spring, when the switch is in the off position being such as toform a V- with each of said arms, the

movement of said carrier when the traverse is moved to the on position producing furthercompression. of the spring while the resultant arm on which the. spring works is reduced.

9-. An electromagnetic switch as defined in claim 5., in which the cooperating contacts actuated by said carrier contact the auxiliary fixed contacts earlier, and break said contacts later, than the time of making and breaking the main contacts of said switch.

10. An electromagnetic switch as defined in claim 5, in which the pair of cooperating contacts 5 6 actuated by the carrier is mounted for vertical REFERENCES CITED reciprocation, and in which said cooperating con- The following references are of record in the tacts are mounted on a vertically movable memfile of this patent. her having openings therein, and in which the carrier is provided with arms which enter the 5 UNITED STATES PATENTS openings in said member, movement of said car- N b Name Date rier by said traverse moving said arms to efiect 1,01 ,329 Jones Feb 1912 vertical reciprocation of said member and the 2 013 013 v Va1kenburg t. 3 1935 a ts c rried y- 2,239,031 Bierenfeld Apr. 22, 1941 10 2,254,768 Bierenfeld Sept. 2, 1941 ERNST BESAG- 2,283,795 Dahl May 19, 1942 WALTER EDWARD HILL- 2,304,972 Van Valkenburg Dec. 15, 1942 THOMAS DANIEL GUY WINTLE- 2,308,433 McLoughlin et a1. Jan. 12,1943

2,433,710 Schleicher Dec. 30, 1947 

